Draw an isosceles triangle on a piece of paper using a pencil. The triangle should be 10 inches high, and 4 inches wide at the base.
Cut out the triangle using a pair of scissors. This is your paper template.
Cut out a polar fleece triangle by laying the paper template on the fabric and cutting around it. Using polar fleece enables you to avoid hemming or finishing your pennant curtain.
Turn the 4-inch edge down by 1 inch toward the wrong side of the fabric and sew it flat. This gives you a triangle with a tube across the shortest edge.
Trim the sides of the triangle with a pair of scissors so that it is a perfect isosceles triangle again.
Thread the triangle onto the curtain rod.
Repeat Steps 3 through 6 until there are enough pennants to cover the curtain rod. At this point you are ready to reattach the curtain rod to the window.